A variety of brain pathologies can give rise to severe memory impairment, the most common being the following:
1. degenerative disorders (particularly Alzheimer' disease and Huntington' disease);
2. chronic alcohol abuse giving rise to Korsakoff' syndrome;
3. traumatic head injury;
4. temporal lobe surgery;
6. cerebral vascular disorders (including subarachnoid haemorrhage resulting from ruptured aneurysms);
7. anoxic brain damage (following, for example, myocardial infarction, carbon monoxide poisoning, or respiratory arrest);
These conditions are described in the chapters in Section 4.1 of this book and in more detail in a number of publications: Kapur (4) and Lishman(5) both provide good accounts of all these pathologies as well as less common ones.
Clients referred to rehabilitation centres for memory-therapy rehabilitation are most likely to have sustained a severe traumatic head injury, a cerebral vascular accident (CVA), herpes simplex encephalitis, or anoxic brain damage. It should also be remembered that these conditions are not mutually exclusive. I once saw a man who had a CVA while driving, thus sustaining some brain damage from the stroke; he then crashed his car because of the CVA and sustained further brain damage from a head injury caused by the crash; following this he stopped breathing for a while and appeared to sustain further damage from the anoxia; then on top of everything else a haematoma developed and the man required surgery to remove the blood clot. Thus he sustained damage from four separate causes. He went on to respond reasonably well to rehabilitation and, although never able to return to work as a university lecturer, he became a secretary of his local Headway Group (The National Head Injuries Association).
Whatever the cause of the organic memory impairment, certain characteristics tend to be seen in survivors. People with a classic amnesic syndrome show an anterograde amnesia, that is they have great difficulty learning and remembering most kinds of new information. Immediate memory, however, is normal when this is assessed by forward digit span or the recency effect in free recall. There is usually a period of retrograde amnesia. This gap or period of retrograde amnesia is very variable in length and may range from a few minutes to decades. Previously acquired semantic knowledge and implicit memory (remembering without awareness or conscious recollection) are typically intact in amnesic subjects. Other cognitive skills, apart from memory, are normal or nearly normal. As the majority of patients with severe memory disorders present with additional cognitive problems such as attention deficits, word-finding problems, or slowed information processing, those with a classic amnesic syndrome are relatively rare.
Nevertheless, people with a 'pure' amnesic syndrome and people with more widespread cognitive deficits tend to share certain characteristics. In both cases immediate memory is reasonably normal; there is difficulty remembering after a delay or distraction; new learning is difficult, and there is a tendency to remember things that happened a long time before the accident or illness better than things that happened a short time before. People with organic amnesia never seem to lose memory for personal identity, unlike those with a functional amnesia following, say, an emotional trauma. Despite the rather exaggerated interest in functional amnesia by the media, organic amnesia is far more commonly encountered in clinical practice. In some cases it is not easy to distinguish between the two, and indeed some people have memory problems resulting from both brain injury and from an overlying or functional memory disorder, possibly caused by a need for sympathy or some other secondary gain. Kopelman(6) believes there is a continuum between totally organic amnesia and totally functional problems rather than two orthogonal dimensions.
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Alcoholism is something that can't be formed in easy terms. Alcoholism as a whole refers to the circumstance whereby there's an obsession in man to keep ingesting beverages with alcohol content which is injurious to health. The circumstance of alcoholism doesn't let the person addicted have any command over ingestion despite being cognizant of the damaging consequences ensuing from it.